JPS5864740A - Electron-gun electrode structure - Google Patents

Abstract

PURPOSE:To enhance the resolutional characteristic of a main electron lens by locating the second electrode with completely circular holes inside the first electrode, which is provided with defectively-circular-shaped overlapped openings and used as a main electrode body, in such a manner that the holes of these electrodes are coaxial to each other. CONSTITUTION:Since the overlapped parts with a hole diameter D0 are cut at the opening part of a focusing electrode 20, three openings 21R-21B become continuous, and the periphery of the continuous openings 21R-21B is surrounded by a continuous protruding margin 22, which has a height hO and constricted parts at the overlapped parts of the openings 21R-21B. Inside the electrode 20, at a part distant from a closed surface 23 by 0.4-0.7 time the diameter D0, a closed cylindrical electrode 30, the closed surface 33 of which is provided with openings 31R-31B each of which has a hole diameter D1 and is surrounded by a protruding margin 32 with a height h1 and which have centered points apart from each other by S, is installed so that the openings 31R-31B and the defectively-circular-shaped overlapped openings 21R-21B are coaxial to each other. Owing to the above constitution, the extension of the diameters of electron beams caused due to the spherical aberration is reduced, and the resolutional characteristic of a main electron lens can be remarkably enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the resolution of an electron lens for an in-line color receiver tube electron gun.

The resolution characteristics of an electron gun for a picture tube are mainly restricted by the spherical aberration of the electron lens, and in order to obtain high resolution characteristics, it is necessary to increase the diameter of the electrode constituting the main electron lens to reduce the spherical aberration of the electron lens. In an in-line electron gun in which three apertures through which the electron beam passes are arranged in a straight line, simply increasing the diameter of the main electron lens increases the eccentric distance between the apertures, and also increases the distance between the electron guns. The diameter of the receiving pipe must be increased. As is well known, an increase in the eccentric distance deteriorates the convergence characteristic of concentrating two electron beams over the entire area on the phosphor screen.
An increase in the neck diameter increases the deflection power of the picture tube, which is undesirable.

Therefore, as shown in Figures 1 and 2, in addition to changing the eccentric distance S and neck diameter of the in-line electron gun, a method of increasing the aperture of the main electron lens constituent electrode is to increase the eccentricity of the three apertures. An electrode structure has been proposed in which three apertures having a diameter of 8 or more are arranged in-line by weighting each other.

Fig. 81 shows a top view of the electrode 11 in which the apertures 11R, IIG, and IIB having diameters of three O aperture eccentric distances of 8 or more are arranged in-line by overlapping each other, and each aperture 11R, I
IG and IIB do not form independent apertures, but are continuous communicating holes in their overlapping portions, and 1Eli-shaped partition electrodes 12 are installed at the boundaries of adjacent apertures. FIG. 2 shows a side sectional view of an electron gun assembly in which the electrodes of the above structure are opposed to each other as a focusing electrode G3 and an anode electrode G4 to form a pi-potential focus type main electron lens. As shown in Fig. 1, this main electron lens has apertures in the focusing electrode G3 and anode electrode G4 that are axially symmetrical and are not independent apertures; Because it is
The horizontal lens action is weaker than the vertical lens action, and the beam spot on the phosphor screen becomes more vertically elongated, and the vertical resolution of the central main electron lens is further degraded by both outer main electron lenses. . This deterioration of the stability characteristic becomes more serious in a high current range where the diameter of the electron beam occupying the electron lens increases.

The present invention has been made in view of the above-mentioned drawbacks, and includes at least one set of electrodes each having a plurality of truncated circular overlapping apertures arranged in-line with an aperture diameter greater than 8 in aperture eccentricity. In an electron gun that faces each other to form a main electron lens, the electrodes are located inside the electrodes at a distance of 0.4 to 0.7 times the aperture from the opposing surfaces of the electrodes, and do not overlap each other with the eccentric distance. The present invention provides an electron gun electrode structure in which the resolution characteristics of the main electron lens are improved by arranging electrodes with a plurality of apertures.

An embodiment of the present invention will be described in detail below with reference to the drawings. To simplify the explanation, a pie similar to the conventional example shown in Fig. 2 is used.
A case where the present application is applied to a potential focus type main electron lens will be explained.

That is, FIG. 3 shows a top view of the focusing electrode 2° facing the anode electrode, and FIG. 4 shows a side sectional view thereof. Focusing electrode 20ti
Three occluded circular superimposed apertures 21 arranged in-line with three aperture eccentric distances of 8 or more on the closed surface 23.
It is a closed-base cylindrical body with holes R, 21G, and 21B, and a flange-like edge 24 that also serves as an electrode supporter is integrally formed on the open end side.

In the aperture of the focusing electrode 20, the overlapping part of the aperture D0 is cut off, so that the three apertures 21R, 21G, and 21B communicate with each other, and the overlapping part of the aperture is formed around the three apertures. It is surrounded by a continuous height hρ projecting edge 22 with a constriction.

Furthermore, the eccentric distance S is located inside the focusing electrode 20, which is a distance d that is 0.4 to 0.7 times the aperture diameter from the closed surface 23.
with a diameter D each surrounded by a protruding edge 32 with a height hl.
The second closed cylindrical electrode 30, which has the openings 31B, 31G, and 31B of I, drilled in the closing surface 33, is arranged so that each of the openings and the occluded circular overlapping positive hole are coaxial with each other. It is set up.

hs here? "A D t" is set. In this case, completely circular openings 31R, 31G, 31
The closed cylindrical electrode 30 with B has an occluded circular overlapping positive hole 21R.
, 21G.

It is inserted in a nested manner into a focusing electrode 20 having a diameter 21B, and both are fixed to each other by flanges 34 and 24 on the open end side.

In general, in a cylindrical electrode that is sufficiently longer than the aperture diameter and is held at a certain potential, the range in which the aperture can affect the potential distribution within the cylinder is the inner cloth that is about the diameter of the aperture, and the rate of change in the potential distribution varies depending on the aperture diameter. The cloth inside the cylinder, which is about 0.3 to 0.5 times as large as the inside of the cylinder, is most dominantly affected. However, in the present application, a second electrode having a perfectly circular hole with a diameter D1 smaller than Do is coaxially disposed inside the first electrode at a distance d that is 0.4 to 0.7 times the aperture diameter D0. Therefore, without impairing the effect of reducing spherical aberration near the axis due to the large diameter of the first electrode,
The electric field distortion at the axial edge of the electric field due to the non-axial symmetry of the incomplete circular hole is corrected, and furthermore, the electric field distortion in the axial peripheral part of the electric field due to the non-axial symmetry of the incomplete circular hole is corrected. The electric field has axial symmetry. Therefore, an electron lens formed by opposing electrodes with this structure as a focusing electrode and an anode electrode has extremely small spherical aberration, has homogeneous horizontal and vertical lens action, and has a high electron beam diameter occupied by the electron lens. Resolution characteristics are significantly improved up to the current range. Further, according to the embodiment of the present application, there is no need to install a partition stain pole at the boundary between the communicating hole and the adjacent hole of the overlapping truncated circular hole.

As described above, in an electron gun using the electrode structure of the present invention, a second electrode having a complete circular hole is disposed coaxially inside the first electrode, which is an electrode body having a circular overlapping hole. This makes it possible to form a large-diameter main electron lens that is substantially axially symmetrical, reducing the expansion of the electron beam diameter due to spherical aberration and significantly improving the resolution rit characteristics of the main electron lens. I can do it.

In the above description, the second closed cylindrical electrode with a complete circular hole is fixed in a nested manner within the first closed cylindrical electrode of the electrode body, but the fixation of both is limited to this. Any fixing method can be used as long as the structure is such that the complete circular hole faces the occluded circular overlapping hole at a predetermined distance d.

It goes without saying that the main electron lens is not limited to the pi-e potential focus type, but can also be applied to a unipotential focus type or other composite multi-stage focusing type electron lens.

[Brief explanation of the drawing]

Fig. 1 is a top view of a conventional electrode with apertures having an aperture greater than the eccentricity of three apertures and which are overlapped with each other and arranged in-line, and Fig. 2 is a top view of an electrode with the above structure. FIG. 3 is a top view of the focusing electrode according to an embodiment of the present invention, and FIG. 4 is its side. A sectional view is shown respectively. 11... Conventional closed cylindrical electrode with overlapping incomplete circular holes, 12... Partition electrode, 20...
...Focusing electrode, 21R, 21G, 21B...
Missing circular superimposed opening, 30...Second closed cylindrical body electrode with complete circular opening, 31R131G, 31B
・・・・・・Complete circular hole opening, 22.32・・・・・・
salient margin. C.C.

Claims (1)

[Claims] In an electron gun in which a main electron lens is formed by mutually opposing at least one set of electrodes each having a plurality of omitted circular overlapping apertures arranged in-line with an aperture larger than the eccentric distance of the aperture, 0.4 to 0.7 of the diameter from the opposing surface of each of the electrodes.
An electron gun electrode assembly characterized in that an electrode having a plurality of completely circular apertures that are spaced apart from each other and having the same eccentric distance and that do not overlap each other is arranged coaxially within the electrode.